1. Field of the Invention
The present invention relates generally to an image reproducing apparatus and method, and more particularly, to an apparatus for and a method of reproducing digital image data transmitted through a transmission line.
2. Description of the Related Art
Image data is handled after being subjected to data compression processing in many cases because the quantity thereof is significantly large. In a system for transmitting compressed digital image data through a transmission line with a relatively low speed such as a digital public network, it is necessary to wait, so as to reproduce and display compressed image data received on the receiving side, for the completion of the receiving of the whole compressed image data. The quantity of the image data is relatively large even if the image data is subjected to data compression, as described above. Accordingly, it takes a very long time (for example, not less than 10 seconds) to complete the receiving of the whole image data, particularly when the transmission speed is low. A receiving person feels the waiting time very long.
Therefore, a method of reproducing and displaying, during the receiving of image data, only a received part of the image data is considered. Examples of this method include 1) a method of first transmitting only a DC component of image data to first display a rough image represented by the DC component, 2) a method of first transmitting data representing upper bits of image data which is not compressed to first display a rough image represented by upper bits, and the like.
However, the following problems arise in the above-mentioned methods. That is, in the method 1), the compression rate of the image data cannot be increased. In the method 2), the image data cannot be compressed. In either method, therefore, although a rough image can be displayed during the receiving of the image data, it takes still longer to complete the receiving of the whole image data.